1. Field of the Invention
The present invention relates to a waveguide-type optical semiconductor device.
2. Description of the Related Art
Japanese Unexamined Patent Application Publication No. 8-220358 discloses a waveguide-type optical semiconductor device provided with a ridge waveguide. In this document, grooves (stripe-shaped grooves) are formed by etching to form ridge portions on both sides of the ridge waveguide. The etched grooves are filled with a material other than a semiconductor material for planarization. In addition, the width of each of the etched grooves is designed to an optimal value. As a result, the high-power performance and reliability of the optical semiconductor device can be improved.